1. Field of the Invention
The present invention relates to a keyboard input device having a pointing device for controlling the cursor position on a graphic display device and the like.
2. Description of the Related Art
In general, pointing devices, such as mice or trackballs, which are provided separately from keyboard input devices, are widely used in graphic display devices and the like. In this case, not only is space necessary for mounting the keyboard input device, but space is also necessary for mounting the pointing device, and this increases the footprint of the overall graphic display device.
Accordingly, Japanese Unexamined Patent Application No. 6-32421 discloses a combination of a keyboard input device having a plurality of control keys arranged in order and a pointing device having strain gauges, in which the pointing device is incorporated in the keyboard input device.
Such a keyboard input device integrally provided with a pointing device has the advantages of a smaller footprint and easier carrying, and demand therefor is increasing in the fields of portable personal computers and the like in which miniaturization is extremely important.
As shown in FIGS. 9 and 10, a pointing device 20 integrally incorporated in a conventional keyboard input device includes a control member 23 having a flat pedestal 21 at the bottom, and a prismatic operating portion 22 projecting upward from the center of the pedestal 21.
Strain gauges 24, such as resistors, are bonded on four outer side faces of the operating portion 22, and are connected to terminal portions 25a of a flexible substrate 25. A cap 26 is mounted on the top end of the operating portion 22.
The pointing device 20 having such a configuration is mounted on a metal plate 30 by directly mounting the pedestal 21 on the metal plate 30 and folding support pieces 30a, which are formed on the metal plate 30 by louvering, onto recesses 21a of the pedestal 21.
A plurality of control keys are arrayed on a plurality of contact portions (not shown) formed on a membrane switch 31. The cap 26 of the pointing device 20 is exposed, surrounded by a plurality of control keys.
The contact portions of the membrane switch 31 are turned on and off by operating the control keys. When the operating portion 22 is tilted or bent by imposing a load on the cap 26 of the pointing device 20 in the direction of the arrow in FIG. 10, the four strain gauges 24 are tensioned or compressed by the bending, and the voltages thereof change. A cursor on a display (not shown) can thereby be moved to a desired position in accordance with the amount of change in the voltages.
Such recent keyboard input devices, particularly those to be incorporated into notebook personal computers, must have low profiles. In order to achieve a low profile, it is necessary to reduce the height of the control keys and the height of the operating portion 22 in the pointing device 20.
However, height reduction of the operating portion 22 makes it difficult to mount the strain gauges 24 thereon.
For this reason, a keyboard input device has been proposed in which strain gauges are mounted on the upper surface or lower surface of a flat pedestal, a control member is tilted by applying load on an operating portion so as to bend the pedestal, and the bending of the pedestal is detected by the strain gauges.
If the pointing device having the strain gauges attached to the upper or lower surface of the pedestal is directly mounted on a metal plate by bending support pieces in the above-described manner, the force of bending of the support pieces is applied in a direction parallel to the pedestal, and thereby acts on the strain gauges. This makes it difficult to cause the strain gauges to function precisely, and to move the cursor on the display with accuracy.
In view of the above problems, an object of the present invention is to provide a keyboard input device in which a pointing device is mounted on a metal plate so that the strain gauges can function precisely.
According to one aspect of the present invention, there is provided a keyboard input device including: a membrane switch having a plurality of contacts; a plurality of control keys arranged on the contacts so as to operate the membrane switch; a base for placing the membrane switch thereon; and a pointing device mounted on the base and having a control member including an operating portion and a plurality of sensing elements, the control member being mounted on a mounting member, wherein one of the mounting member and the base has a hole, the other has a projection, the pointing device is mounted on the base by joining the projection and the hole by caulking, and the operating portion of the pointing device is placed among the plurality of control keys.
In the keyboard input device, one of the mounting member and the base has a hole, the other has a projection, the pointing device is mounted on the base by joining the projection and the hole by caulking, and the operating portion of the pointing device is placed among the plurality of control keys. Therefore, it is possible to provide a keyboard input device in which the mounting member can be mounted on the base without applying unnecessary load on the sensing elements, the beam portions can be reliably bent in response to the load applied on the operating portion, and the bending of the beam portions can be precisely detected by the sensing elements.
Preferably, the base and the mounting member are made of metal, and the projection is formed by burring or drawing.
In this case, working of the base is facilitated. Moreover, since the mounting member to be mounted on the base by caulking is made of metal, it is possible to increase the caulking strength of the projections, and to thereby reliably mount the pointing device on the base.
According to another aspect of the present invention, there is provided a keyboard input device including: a membrane switch having a plurality of contacts; a plurality of control keys arranged on the contacts so as to operate the membrane switch; a base for placing the membrane switch thereon; and a pointing device mounted on the base and having a control member including an operating portion and a plurality of sensing elements, the control member being mounted on a mounting member, wherein the mounting member and the base have holes, an eyelet or a rivet is passed through the holes in mutual alignment, and the pointing device is mounted on the base by caulking the eyelet or rivet.
The mounting member and the base have holes, and an eyelet or a rivet is passed through the holes in mutual alignment and is caulked, thereby mounting the pointing device on the base. Therefore, it is possible to provide a keyboard input device that further facilitates working of the base.
The mounting member may be mounted on the upper surface of the base.
In this case, the projection of the base and the hole of the mounting member can be aligned and assembled while being visually checked when mounting the pointing device on the base, which provides a keyboard input device having superior assembly characteristics.
The mounting member may be mounted on the lower surface of the base.
In this case, it is possible to make wide use of the upper surface of the base adjacent to the pointing device, and to increase the degree of flexibility in arranging the control keys.
Furthermore, even when the height of the control keys is further reduced, the amount of protrusion of the pointing device above the control keys can be also reduced, and therefore, the pointing device is also applicable to a low-profile keyboard input device.
Further objects, features, and advantages of the present invention will be apparent from the following description of the preferred embodiments with reference to the attached drawings.